Cumulative evidence from research on sex differences in the incidence of cognitive and behavioral disorders in children suggests increased male vulnerability to deviation from normal development. This gender difference has been ascribed to adverse obstetric and perinatal events which may culminate in central nervous system (CNS) injury. In the proposed study, the maturational account of sex differences in vulnerability to developmental deviation will be used as a heuristic model to generate specific outcome predictions. The main objective of the planned project is to provide a better understanding of the nature of sex differences in cognitive outcome of early CNS injury. Subependymal, germinal matrix hemorrhage - an insult occurring in up to 40% of preterm infants below 32 weeks gestation - will be used as a model of early CNS lesion. The insult may be reliably diagnosed by cranial ultrasonography. In a prospective investigation, 120 male and female infants with intracranial hemorrhage and 120 controls will receive a follow-up sonogram after the resolution of the insult. The degree of persistent ventriculomegaly - an indirect index of cerebral tissue loss - will be estimated from the ultrasound scans using computer-assisted morphometry. The subjects will then undergo a series of infant mental ability tests. The following specific questions will be addressed in the proposed investigation; 1. Are there sex differences in development of cognitive skills following perinatal intracranial hemorrhage? 2. If so, are these differences independent of the number or severity of common anti-, peri-, and post-partum complications? 3. Do the putative sex differences depend on the severity of the lesion? 4. Are the putative sex differences associated with the extent of structural cerebral change following the resolution of the lesion?